(12:08 p.m. EST) -- Anyone who has ever cruised is familiar with the muster drill. Vacation fun is put on hold as the powers-that-be close the bars and order passengers to gather at an assigned meeting place for a lesson on how to don a life jacket and what to do in case of an emergency.

While many people listen attentively, every muster has a few of these types: The guy swilling a beer and laughing with his buddies, even though passengers have been told no drinking is allowed during the drill. The couple who hide in their cabin, thinking they've pulled one over on the authorities. The mom and her kids who stand in the back of the lounge during the presentation and sneak out after a few minutes.

Even some of the most flagrant violators must be rethinking that behavior in light of the Costa Concordia disaster. But inattention at the muster drill played no part in this tragedy. The drill had not yet been held for the 696 passengers who boarded in Rome, even though the ship was some three hours out of port and passengers were eating dinner when the accident occurred. Yet the ship appears to have been in compliance with muster drill requirements.

So what exactly must cruise ships do to ensure that passengers are educated about emergency evacuation procedures? Cruise Critic examined the rules and regulations, and interviewed representatives of governing agencies and the major cruise lines, to figure out the nitty-gritty on these drills.

All cruise lines have to follow regulations called Safety of Life at Sea (SOLAS), which were adopted following the sinking of the Titanic and are administered by the United Nation's International Maritime Organization (IMO). The U.S. Coast Guard also gets involved by making sure those regulations are followed by passenger ships that stop in the United States.

The SOLAS regulations pertaining to muster drills are fairly short and straightforward. They require that the drill take place within 24 hours of embarkation. The regulations differentiate between a muster and a "safety briefing." According to SOLAS rules, whenever new passengers embark, a safety briefing must be held "immediately before sailing, or immediately after sailing," consisting of at least a PA announcement. This may be supplemented with other info -- by written materials contained within each cabin, for instance. Regulations require that the safety briefing provides "clear instructions" that "detail the actions each person on board should follow in the event of an emergency." But a muster, where passengers are physically assembled, is required only within 24 hours of sailing. (In Concordia's case, the muster drill was scheduled to take place after additional passengers boarded on Day 2 in Savona, Italy, which would have been within the required 24-hour window.)

As for life jackets, the rules don't specifically say that passengers must don them during the drills -- but they must be shown how to put them on.

In recent years, lines with bigger ships, including Royal Caribbean and Carnival, have concluded that moving upward of 5,000 passengers, outfitted in bulky life jackets, to their muster stations had become unmanageable. These lines have instituted a new version of the muster drill. According to Bud Darr, director of environmental and health programs for the Cruise Line International Association (CLIA), a membership organization that represents the major cruise lines, passengers now assemble in large public rooms, instead of on the open decks, where they await further instructions.

On some ships, including Royal Caribbean's Oasis of the Seas and Allure of the Seas, life jackets are kept at the muster stations rather than in individual cabins; ship safety officials made the switch for a couple reasons. One was that in a real emergency, forcing thousands of passengers back to their cabins to grab their life vests would work against an evacuation. Another had to do with dangerous dangling belts. "'Slips, trips and falls' during the drills was one of the most cited reasons cruise lines gave us for the change," said Brad Schoenwald, Senior Marine Inspector for the U.S. Coast Guard's Cruise Ship National Center of Expertise. "Passengers would slip on a belt strap on the way down the stairs, and you'd potentially have an injury."

As to when the drills are held, Darr said the norm, at least in most major lines that cater to American passengers, is to hold the muster drill and safety briefing simultaneously before the ship embarks. This way, the lines can cover both requirements at one time. But, again, maritime regulations require only that a safety briefing be held "immediately before sailing, or immediately after sailing," and that the muster be held within 24 hours. So some cruise ships, such as Costa Concordia, that stop at multiple ports to pick up passengers, do not hold a muster until some passengers have already been onboard overnight.

"The important thing is that each line has standard methods and procedures and a well-trained crew," Darr said.

To that end, the Carnival Corporation -- parent company of Costa, as well as nine other cruise lines -- announced that it will conduct "a comprehensive audit and review of all safety and emergency response procedures across all of the company's cruise lines." Captain James Hunn, a retired U.S. Navy Captain and Carnival's senior vice president of Maritime Policy & Compliance, will lead the effort, working with health and safety executives from the Carnival Corporation cruise lines and outside experts. The team, according to the company statement, "will review all safety and emergency response policies and procedures, officer and crew training and evaluation, bridge management and company-wide response and support efforts." The goal is to identify the best practices to put in place to make sure that a Concordia-like incident does not happen again.

In addition, the Cruise Lines International Association (CLIA) will also be conducting an industry-wide operational safety review, which will include internal reviews by the organization's 26 cruise line members, consultation with experts and regulatory agencies, and the development and sharing of best practices.

We reached out to various cruise lines to find out how they interpret safety regulations and handle mustering, but most weren't that forthcoming about the details. Several, including Crystal Cruises, Disney Cruise Line, Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises, would not comment, referring all questions to CLIA. At press time, Costa has not responded to our requests for information. However, several others did respond, and here is the official word, albeit often quite generic, from each of the other major lines:

Azamara Club Cruises, Royal Caribbean International and Celebrity Cruises (all part of the Royal Caribbean Cruises Ltd. brand): All passengers and crew must complete an abandon ship drill "at the beginning of each voyage." Muster drills are conducted without passengers donning life jackets. On Royal Caribbean's largest ships, Oasis and Allure of the Seas, life jackets are held at muster stations to be distributed by crewmembers in case of emergency, rather than in cabins; on other ships, life jackets are also kept in cabins, and in emergencies, crew will make sure life jackets are distributed at the muster stations. To ensure that passengers are aware of their specific muster location, each cabin key is individually imprinted with that location. The location is also noted on the back of each cabin door. Officers and crewmembers additionally conduct weekly, monthly and annual drills to train and prepare in case of emergencies. All ships have enough lifesaving craft to accommodate every person onboard, with additional reserve capacity.

Carnival Cruise Lines: "Normal procedure" is to conduct the safety drill prior to departure. The safety briefing is held at dedicated muster stations where crewmembers demonstrate how to wear life jackets. Passengers are not required to wear life jackets during muster; life jackets are kept in the cabins. The briefing is conducted in English, but may also be conducted in other languages if there are a significant number of passengers from a particular country or region. During the drill, every cabin is checked by cabin stewards and a red card is placed in each key slot showing that no guests are present inside. Written materials, available in different languages, are also provided. A safety video, which is played nonstop during the drill, is available via in-cabin TV; it outlines evacuation routes, muster station locations, assistance for physically challenged guests, life jacket instructions, etc. Lifeboats are tested during regularly scheduled drills to make sure they are in proper working order. A full-scale life boat exercise, during which lifeboats are launched and maneuvered in the water by assigned crew, is conducted each month, exceeding the quarterly regulatory requirement.

Cunard Line: The line adheres to the SOLAS requirement that a safety drill be held within 24 hours, and "in many instances" the drill is conducted prior to sailing. Each passenger is assigned a specific area to muster and the use of life jackets is demonstrated and practiced during the drill, which also instructs passengers regarding what to do and where to go in case of an emergency. Crew proficiencies are verified during drills and exercises, including periodic exercises with the U.S. Coast Guard.

Holland America Line: The line follows international maritime law by requiring a mandatory lifeboat drill for all passengers within 24 hours of departure. "In many instances," the drill is conducted prior to sailing.

MSC Cruises: Upon embarkation in the main ports, passengers participate in a one-hour muster drill conducted in six official languages, and any other language spoken by a guest. Passengers take their life jackets from their staterooms and go to their assigned muster station. The drill involves the entire crew and simulates the evacuation process. Staterooms are checked during the drill. In secondary ports, before the ship's departure, a detailed safety briefing is held for all newly embarked passengers. The briefing is normally held in a dedicated area, usually the theater or a muster station. Each passenger's muster station is printed on his/her stateroom key. Written safety materials include maps of the muster stations displayed in all public areas, a safety page within the cabin's booklet that is left open and is pointed out by the housekeeper, and maps on the back of each stateroom door with instructions in six languages. A safety video in English is broadcast 24/7 on the stateroom television system on Channel 1. Children ages 12 and younger are given a bracelet at embarkation to wear with their muster station printed on it.

Princess Cruises: Muster drills are held before departure "whenever possible." Passengers are sent to their respective muster stations, which may be in a public room or near the lifeboat embarkation deck. Passengers wear life jackets during the drill. Passengers are required to attend, but a safety video covering evacuation procedures is also played on the in-cabin television. If a large number of passengers speaking a language other than English is onboard, a separate drill is held in that language. Each stateroom has a map of the route to its muster station, and signs are also posted on the staircases.

Seabourn: The line follows international maritime law by requiring a mandatory lifeboat drill for all passengers within 24 hours of embarkation. "In many instances," the drills are conducted prior to departure. Passengers are instructed where to go and what to do in case of an emergency.